Preparation And Microstructure Evolution Of ZK60 Nanocrystalline Magnesium Alloy Concerning Hydrogenation-dehydrogenation Processing

In 21 st century, automobile manufacturing, aviation electronics and other fields show strong demand for the metal materials. With the advantages of rich reserves and light weight, magnes ium and its alloys attract adequate attention. However, the low absolute intensity, poor room temperature ductility, weak corrosion resistance and active chemical feature greatly restricted its further applications. On the other hand, environmental pollution, energy consumption and other global issues are also prompting the development of metal materials toward the light weight and strong comprehensive performance. Therefore, the strengthening of magnes ium alloys becomes an inevitable trend.Measures to strengthen the alloy currently have been studied a lot, including strengthening alloying elements, grain strengthening and rapid solidification strengthen ing. Described herein is to achieve enhanced overall performance through grain refinement.This article has vestigated the influence of temperature, hydrogen pressure, and reaction time during the hydrogenation-disproportionation-desorptionrecombination(HDDR) processes. The results show that, temperature plays the most important role in the HDDR process. In the hydrogenation stage, the hydrogen pressure and reaction time can promote hydrogenating based on the condition of temperature exceeding a certain threshold. The reaction temperature must be strictly restricted in an appropriate range of values. In the dehydrogenation stage, completely dehydrogenation requires a certain temperature and reaction time. The best technical parameters that can be used to get fully hydrogenated are at 350℃, 2 MPa hydrogen pressure incubated 12 h, afterwards evacuated at 350℃ for 3 h to get completely dehydrogenated, with this technology can be ZK60 alloy powder refined from 160 μm to about 20 nm.In the process of exploring ZK60 alloy fully hydrogenateddehydrogenation technology, XRD、OM、SEM and TEM techniques were used to investigate the evolution of the texture and structure of magnesium alloy during the hydrogenation-dehydrogenation process. By observing the phase composition, grain size and other internal structures of ZK60 alloy powder, the hydrogenation-dehydrogenation mechanism of grain refinement was studied. Furthermore, hydrogenation-dehydrogenation of block ZK60 magnesium alloy was also studied in an attempt to understand the principles of HDDR process. With the contrast of pure magnes ium, it can be drawn alloying elements Zn and Zr in ZK60 magnes ium alloy for hydrogenation-dehydrogenation show little effect on the conclusions, so that ZK60 alloy hydrogenation-disproportionationdehydrogenation-recombination stage can be simplified as hydrogenation-dehydrogenation(HD) process.